1. Field of the Invention
The present invention relates to a wire bonding unit for automatically connecting electrodes of an element, such as a semi-conductor element, to fine wires.
2. Description of the Prior Art
The conventional wire bonding apparatus is usually operated manually. The operator examines the portion to be bonded with his naked eye or with a microscope, positions said portion to be bonded beneath the bonding head and brings down said bonding head on said portion so as to bond said portion to the external lead. In the conventional wire bonding apparatus, the positioning of the bonding portion is carried out with the naked eye only. Therefore, when the electrodes create a very fine pattern, a skilled workman is required for carrying out the bonding operation. Consequently, it is very difficult to complete a fine bonding operation in a very short time.
To obviate the above-mentioned drawback, the following described operation is carried out and therein a semi-automatic wire bonding apparatus is utilized. That is to say, when an element has many electrode terminals to be bonded, such as an integrating circuit element, one terminal is selected as the reference terminal and positioned manually. With respect to the other terminals, the positioning is carried out automatically by a predetermined program. This automatic operation of the semi-automatic wire bonding apparatus is based on the fact that the positions of said other terminals have a predetermined regularity with respect to the reference terminal. However, in the case where the positional relationships between the reference terminal and the other terminals are not accurate, the bonding position will not coincide with the predetermined position to be bonded. Therefore, it is necessary to continuously inspect whether or not the apparatus is operating correctly.